Problem: Evaluate the following expression when $a = 9$ and $b = 2$. $4$ $a$ $^2 + 4$ $b$ $ - 9$
Explanation: Substitute $9$ for ${a}$ and $2$ for ${b}$ $ = 4{(9)}^2 + 4{(2)} - 9 $ Remember order of operations. Evaluate the exponent before you multiply. $ = 4(81) + 4{(2)} - 9 $ $ = 324 + 8 - 9 $ $ = 323$